The invention described herein was made in the performance of work under a NASA contract, and is subject to the provisions of Public Law 96-517 (35 U.S.C. 202) in which the Contractor has elected to retain title.
Velocimeters detect velocity of moving elements. They are used in various applications. A miniature velocimeter can be used for detecting particle motion such as in industrial and medical applications. Velocimeters can also be used to detect macro motion, such as detecting the roughness of a surface, for example. Various other industrial applications are possible; such as detecting movements of belts, or the motion of a surface via its surface roughness, for example.
Laser Doppler velocimeters are commercially available. Such systems, are described, for example, in U.S. Pat. Nos. 5,557,407; 5,552,879; 5,483,332; 5,587,785; 5,013,928; 5,216,478; 5,187,538; 5,737,070; 5,199,298; 4,896,098; and 5,052,228. These generally use a gas laser and discrete optics. The instrument is large and not susceptible for easy relocation. The instruments are fragile, and typically not suitable for application in harsh environments.
Optical systems of this type have required beam alignment for the transmitting optics. Vibration and temperature changes can cause misalignment in such systems.
A diode-based laser velocimeter has been suggested. This could result in a smaller, more integrated probe.
The present application describes a self aligning optical is probe with a reduced element count and a relatively small overall size. The probe can be used in environments that were not previously accessible with such a device.
In one embodiment, a laser velocimeter probe is defined that has a housing defining an interior chamber, and having first and second ends, a laser source, located in the housing and directed toward the second end, and an optical element, also located in said housing between said laser and the second end. The optical element includes at least a focusing element and a grating. A light receiver is also located in the housing, and receives scattered light from a direction of the second end.